And what is in the Bible and the Qur'an about God is also true.
Baha'is believe that much of the Bible and the Qur'an should be taken metaphorically, even if they agree with much of what they say about God. In this way Baha'is are as much Christian as many liberal denominations of Christianity are, who blatantly disregard many scriptures that say things like 1 - Jesus is the only way to Heaven 2 - Women cannot be pastors 3 - Homosexuality should be viewed as sinful. Among other changes. The difference between liberal Christianity and the Baha'i Faith is that the Baha'is added their own scriptures to work together with the other scriptures. If you don't know community Baha'is have created a program called Ocean that explores various scriptures deemed notable enough to be part of the canon, even if they aren't specifically from the Baha'i Faith.
Baha'u'llah had the privilege, and yes, I say
privilege, to live in the 19th century, where people were starting to understand themselves and the world around them so much more than they used to. If you ask Baha'is what is the meaning of life, many Baha'is would probably say to foster the unity of humanity. I believe this is the
current goal of humanity, but the
ultimate goal that we've been working on since we became self aware is to raise and cultivate as much life under our dominion as possible. Extrapolating this, I could say that in the future it will be the job of these humans to create as much unique life in the Universe as possible, as well as maintaining the sovereignty and the sovereign unity of our species.
@CG Didymus , as far as "why doesn't God show himself" arguments, if He did that, most monotheistic Abrahamics would probably agree that if that happened it would prevent humans from having their free will. If God
forced people to believe in Him, in one way or the other, it would ruin any real amount of free will humans have. God gave us free will, therefore, God Himself doesn't have the free will to remove the free will of humans. It would mean a lot more to God, I would think, if someone believed because they wanted to, rather than being forced or coherence to do so. The argument could then be made that, well, if God showed himself to Baha'u'llah, then he removed His free will by doing so.
Baha'u'llah always had the ability to ignore that conviction of God that was part of his own being. He didn't have to start a world religion and he could have continued his life without being a prophet. God didn't remove his free will by showing Himself to him because the way he showed Himself to him was done in such a subjective matter, just like how many people know and understand God. That's mainly how God expresses himself, in subjective ways rather than being able to definitively measure these types of things. Baha'u'llah didn't ignore these subjective ways God showed Himself to him, and thus, a new religion rose out of the Twelver Shi'a Islam prophecy.
Do I believe in Baha'u'llah? Well, I believe that every human in some way is a manifestation of God. I believe in continuing progressive revelation to this day, and I believe there are objective morals that many of us are blind to see, just like the Baha'is. However, there are many things I disagree with about this religion too. Although not part of covenant-breaking, it is taboo in the religion to join a political party, which means chances are there will never be a President or Prime Minister in any democratic republic that believes in the Baha'i Faith. I also don't agree with fasting or obligatory prayers. Prayers mean more when they are sent in the time of need, not forced to by the convictions of someone else. Prayer should also be customized and tailored to each individual, not a forced set of things someone must recite on a daily basis. Overall I am more focused on beliefs than I am on ritual, but the Baha'i Faith stresses various rituals, even though only a tenth of Baha'is actually seek community within their religion.
Despite my differences from this religion I realize and understand the importance of their mission. Considered apostates from Islam they are probably bringing
less unity to God as a whole by inventing a new way to practice their monotheistic faith, I do not believe that unity simply means everybody believes in the same religion. Contrary to that, I actually think unity is the respect and inclusion of diverse beliefs. This is why while I don't believe there will be a "one-nation world government" anytime soon, sovereign unity can happen with the 200+ sovereign nations that exist and are part of the UN. Unity is simply another word to describe the ideal that Jesus brought to us, by loving thy neighbor. Loving thy neighbor, even though he may be and think differently from you, is another way to express the idea of unity, and because of this, even though both religions came from different times, they ultimately have the same source for their belief - God. And that's the Unity of God and religion the Baha'i Faith has stressed about this entire time.